In recent years, environment has been deteriorated, i.e., a red tide and abnormal quantity of plankton in the lakes and swamps are produced by an increase in inflow amounts of industrial wastewater and sewage accompanied by an increase in population growth. It is considered that such environment deterioration is caused by eutrophication in the lakes and swamps with the nitrogen compound such as ammonia contained in the waste water flowing to the lakes and swamps. The removal of the nitrogen compound from the nitrogen compound-containing water becomes a problem to be addressed urgently.
As one method of solving such problem, there is a treatment method combining the step of adsorbing ammonia by contacting nitrogen compound-containing water with a zeolite based inorganic ion exchanger, and the step of regenerating the exchanger by desorbing the ammonia adsorbed to the inorganic ion exchanger using alkalis or salts, as disclosed in the Japanese Laid-Open Patent Publication 47454/1975. In such treatment method, firstly the sewage or waste water containing the ammonia ions is contacted with the zeolite based inorganic ion exchanger such as Clinoptilolite and mordenite to remove the ammonium ions, whereby the sewage or waste water is made harmless. Then, the ammonium ions adsorbed to the zeolite based inorganic ion exchanger is desorbed with alkalis, salts, or a mixing solution thereof using a conventional method. Alkali is added to the desorbing liquid containing the ammonium ions desorbed to expel them as ammonia gas using air, which is absorbed by a solution of sodium bichromate at normal temperature. The solution is heated and distilled, and distilled components are cooled and condensed to recover as aqueous ammonia.
As described above, the conventional method of treating the ammonia-containing water is to adsorb the ammonium ions to the zeolite based adsorbent, to desorb them into the liquid utilizing alkalis or salts, and to recycle them as the aqueous ammonia. However, the recycling of the ammonia is troublesome as described above, and there is a risk to flow the ammonia outside. The flow of the ammonia significantly affect external environment. Accordingly, there is recently needed to provide a safer method of treating the nitrogen compound-containing water such as the ammonia containing water.